From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0711AC147; Thu, 19 Dec 2024 08:56:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734598582; cv=none; b=t61lQGEPxzWsrw2qElQYx0GvbaNW6OAyeSY8s82nLErffKSZDvAWSHuWwV6MphVz5amq3vm/0j5gXa/kdhduwVzcmCjc5ktk2RU5HisXCxdgwAxrPP+UvVEeugQQ4xuNGyVkj79kYfxc3TV626w9+cfNwKWnqvuus4OX3305D8Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734598582; c=relaxed/simple; bh=F3pUnxpKhsb62P2lfdmS7KpwGkJzfdGous/s5hnmpIc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RmuTAHSAU6bUo7RCOPLn1qnsr9lG/RqvOZ2gHW78vLhrW+fX1VpZzFv5md4ph9hDydg3mL/I63xVQEwu+FUEdD4UddVhXSrTxu9izPS2AoQsGZ9NNM1mCstxJSfuQbmDo01Cs8f6i1QtQDtVtXFZk4dLMXNyiD5epYjb5rRzM/U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1inqtrgE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1inqtrgE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B37BC4CECE; Thu, 19 Dec 2024 08:56:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734598580; bh=F3pUnxpKhsb62P2lfdmS7KpwGkJzfdGous/s5hnmpIc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1inqtrgEafi9/w6YUItFYjkv9kRblD5Tj1SyCmO7BfyKp0gY5e8gOOK12J/RKtuj+ 6W7cPYXn98w6XwYKAmdFi3YeRpuIa0rDIgBNe/rWm8EuyhTmo/zFdrh2bWKOoxrZ6b cIDkCKQ4P+mAfpFN5+DSGEg8h34UJ1h6CWorepbQ= Date: Thu, 19 Dec 2024 09:56:17 +0100 From: Greg KH To: Andre Werner Cc: jirislaby@kernel.org, hvilleneuve@dimonoff.com, andy@kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, lech.perczak@camlingroup.com Subject: Re: [PATCH] serial: sc16is7xx: Add polling feature if no IRQ usage possible Message-ID: <2024121931-turbojet-preamble-b520@gregkh> References: <20241219084638.960253-1-andre.werner@systec-electronic.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241219084638.960253-1-andre.werner@systec-electronic.com> On Thu, Dec 19, 2024 at 09:46:38AM +0100, Andre Werner wrote: > Fall back to polling mode if no interrupt is configured because not > possible. If "interrupts" property is missing in devicetree the driver > uses a delayed worker to pull state of interrupt status registers. > > Signed-off-by: Andre Werner > --- > This driver was tested on Linux 5.10. We had a custom board that was not > able to connect the interrupt port. Only I2C was available. Could you not test this on the latest tree? 5.10 is _VERY_ old now. > --- > --- > drivers/tty/serial/sc16is7xx.c | 40 ++++++++++++++++++++++++++++++++++ > 1 file changed, 40 insertions(+) > > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c > index a3093e09309f..31962fdca178 100644 > --- a/drivers/tty/serial/sc16is7xx.c > +++ b/drivers/tty/serial/sc16is7xx.c > @@ -314,6 +314,7 @@ > #define SC16IS7XX_FIFO_SIZE (64) > #define SC16IS7XX_GPIOS_PER_BANK 4 > > +#define SC16IS7XX_POLL_PERIOD 10 /*ms*/ Please use a tab here. > #define SC16IS7XX_RECONF_MD BIT(0) > #define SC16IS7XX_RECONF_IER BIT(1) > #define SC16IS7XX_RECONF_RS485 BIT(2) > @@ -348,6 +349,9 @@ struct sc16is7xx_port { > u8 mctrl_mask; > struct kthread_worker kworker; > struct task_struct *kworker_task; > + struct kthread_delayed_work poll_work; > + bool polling; > + bool shutdown; > struct sc16is7xx_one p[]; > }; > > @@ -861,6 +865,19 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id) > return IRQ_HANDLED; > } > > +static void sc16is7xx_transmission_poll(struct kthread_work *work) > +{ > + struct sc16is7xx_port *s = container_of(work, struct sc16is7xx_port, poll_work.work); > + > + /* Resuse standard IRQ handler. Interrupt ID is unused in this context. */ > + sc16is7xx_irq(0, s); > + > + /* setup delay based on SC16IS7XX_POLL_PERIOD */ > + if (!s->shutdown) > + kthread_queue_delayed_work(&s->kworker, &s->poll_work, > + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD)); > +} > + > static void sc16is7xx_tx_proc(struct kthread_work *ws) > { > struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port); > @@ -1149,6 +1166,7 @@ static int sc16is7xx_config_rs485(struct uart_port *port, struct ktermios *termi > static int sc16is7xx_startup(struct uart_port *port) > { > struct sc16is7xx_one *one = to_sc16is7xx_one(port, port); > + struct sc16is7xx_port *s = dev_get_drvdata(port->dev); > unsigned int val; > unsigned long flags; > > @@ -1210,6 +1228,11 @@ static int sc16is7xx_startup(struct uart_port *port) > uart_port_lock_irqsave(port, &flags); > sc16is7xx_enable_ms(port); > uart_port_unlock_irqrestore(port, flags); > + if (s->polling) { > + s->shutdown = false; > + kthread_queue_delayed_work(&s->kworker, &s->poll_work, > + msecs_to_jiffies(SC16IS7XX_POLL_PERIOD)); > + } > > return 0; > } > @@ -1232,6 +1255,10 @@ static void sc16is7xx_shutdown(struct uart_port *port) > > sc16is7xx_power(port, 0); > > + if (s->polling) { > + s->shutdown = true; > + kthread_cancel_delayed_work_sync(&s->poll_work); > + } > kthread_flush_worker(&s->kworker); > } > > @@ -1537,7 +1564,13 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, > > /* Always ask for fixed clock rate from a property. */ > device_property_read_u32(dev, "clock-frequency", &uartclk); > + s->polling = !device_property_present(dev, "interrupts"); > > + if (s->polling) { > + dev_warn(dev, > + "No interrupt definition found. Falling back to polling mode.\n"); What is a user supposed to do with this message? And why would a device NOT have any interrupts? This feels like it is just going to pound on the device and cause a lot of power drain for just a simple little uart. Why can't your system provide a valid irq line? thanks, greg k-h